Anion-Controlled Architecture and Photochromism of Naphthalene Diimide-Based Coordination Polymers.

Jian-Jun Liu,Teng Liu,Fei-Xiang Cheng,Yu-Lian Duan,Shu-Biao Xia,Cheng-Ke Sun

doi:10.3390/polym10020165

Abstract

Three new cadmium coordination polymers, namely [Cd(NO3)2(DPNDI)(CH3OH)]·CH3OH (1), [Cd(SCN)2(DPNDI)] (2), and [Cd(DPNDI)2(DMF)2]·2ClO4 (3) (DPNDI = N,N-di(4-pyridyl)-1,4,5,8-naphthalene diimide, DMF = N,N-dimethylformamide) have been synthesized by reactions of DPNDI with Cd(NO3)2, Cd(SCN)2, and Cd(ClO4)2, respectively. Compound 1 is a one-dimensional coordination polymer with strong lone pair-π interactions between the coordinated NO3− anions and the imide ring of DPNDI; while 2 is a two-dimensional network with a (4, 4) net topology. In the case of 3, due to the presence of uncoordinated perchlorate counter ions, it exhibits a non-interpenetrated square-grid coordination polymer containing one-dimensional rhomboid channels. The structural diversity in these compounds is attributed to different coordination abilities and geometries of counter anions. Due to the presence of electron-deficient NDI moiety, the photochromic behavior of these compounds was studied. Interestingly, only compounds 1 and 3 exhibit color changes under light irradiation. The influence of the anions on the photochromism process of the NDI-based materials has been discussed.

Highlights

Due to the versatility of coordination polymers in crystal structures and chemical compositions, they have developed into an important class of materials and enable a wide range of applied properties, such as catalysis, guest/ion-exchange, fluorescence, adsorption, and separation [1,2,3,4,5,6,7,8]
Results and Discussion dihedral angle between Naphthalene diimide (NDI) core and pyridine group is around 83.9°, which is slightly larger than that Crystal of free Structure ligand [38]
Three coordination polymers were successfully constructed from the DPNDI ligand and cadmium ions with different counter anions

Summary

Introduction

Due to the versatility of coordination polymers in crystal structures and chemical compositions, they have developed into an important class of materials and enable a wide range of applied properties, such as catalysis, guest/ion-exchange, fluorescence, adsorption, and separation [1,2,3,4,5,6,7,8]. Many studies on anion-controlled formation of coordination polymers have been reported, very few examples of anion effect on the photochromic properties of coordination polymers have been involved so far because it is usually difficult to create appropriate coordination polymers with photochemical activity, and containing different anions [22,23,24]. Naphthalene diimide (NDI) possess π-conjugated planes, high redox activity, and strong π-acidity, which are excellent candidates of organic ligands for the construction of photochromic coordination polymers due to the controllability of the substituent groups on the diimide

Methods

Results

Conclusion